A computer mouse is a handheld device that a user slides over a suitable surface causing the cursor on a computer screen to move in a direction determined by the motion of the device.
Most all such devices have five components: a ball, two rollers, two encoding disks, a pair of infrared LEDs and infrared sensors, and a microprocessor.
The ball inside the mouse touches most any selected surface and rolls as the device is moved on the surface. The two rollers inside the mouse touch the ball. Each roller rolls in response to a component of motion of the mouse that is orthogonal to the component of motion that drives the other roller. One roller is coupled to one encoding disk and the other roller is coupled to the other encoding disk. Each disk has a circumferential row of apertures. A pair of infrared sensors on one side of each disk detects light from one of a pair of infrared LED on the opposite side of the respective disk and thereby detects rotational displacement of the disk (roller) corresponding to translation of the mouse over the surface in contact with the ball. The processor chip detects the pulses from the sensors and sends the data (by a connecting cord) to the computer.
For each disk, the direction of rotation of the disk is determined by comparing the phases of the optical signals from the respective disk.
The first “optical” disk included a source of a focused beam reflected off a pad onto a sensor. A grid pattern of dark lines was disposed onto the highly reflective surface of the pad. Motion of the pad was detected by interruption of the focused beam by the grid lines.
A limitation of this mouse was the requirement to maintain a specified angle of reflection.
More recently, a so-called “optical” mouse has been disclosed as in U.S. Pat. No. 4,631,400 to Tanner et al and U.S. Pat. No. 6,513,717 to Hannigan.
This optical mouse has a small red light emitting diode (LED) that is reflected off (almost any) surface onto a complimentary metal semiconductor (CMOS sensor, the CMOS sensor sends each signal to a digital signal processor (DSP) for analysis. The DSP operating at 18 mega Instructions per Second is able to detect changes in patterns in the images. The DSP determines how far the mouse has moved by the changing sequences of images, and sends corresponding signals to the computer for control of the cursor. The image signals are received hundreds of times per sec.
The optical mouse, as presently disclosed and marketed has advantages compared to the Opto-mechanical mouse principally in terms of increase tracking resolution and elimination of a requirement for a special tracking surface.
The “form” of these cursor controllers (mice) of the current art are not compatible with the trend of a large segment of the computer market toward the introduction of more “personalized” devices adapted for use where “portability” is an important requirement.
By “form” is meant the physical characteristics of a device such as size, design, shape, weight and power requirements. The “form” therefore, determines the convenience with which the user can operate the device under restricted circumstances. The devices include laptop computers, notebooks, PDAs (personal digital assistants). In the context of this specification, PDA is defined to mean any small handheld device that provides computing, and/or information storage and retrieval capabilities. Since the object in the design of these devices is to provide a device that can be slipped into a pocketbook or shirt pocket, the necessity of using the state of the art optical or opto-mechanical mouse defeats the purpose of the device. The attachment of such devices by cable to the state of the art “mouse” is incompatible with the intended scope of use of the handheld device.
Another problem that is closely associated with the proliferation of PDAs is the protection from theft of the information stored in these devices and the identification of the user. Theft by bank fraud involving false deposits, check forgery has become an enormous problem. The typical response of law enforcement agencies is that a fingerprint is the only certain way to prevent these crimes.
Another problem is that custodians of computers have control over which programs stored in a computer are available for use to only a segment of the public.
For example, a librarian may want to “lease time” that a user uses a particular program on the Internet, computer.
Some photocopying outlets offer desktop publishing facilities.
There are other situations wherein a “public computer” is available for use by the public wherein the computer has stored programs that perform a variety of functions such as web searching, email services, CAD, word processing.
Another problem is that custodians of computers wish to have control over which programs stored in a computer are available for use to only a segment of the public. For example, certain programs may be deemed inappropriate for minors.